Hitachi RAF-25RPA Service Manual page 66

4. Reset Circuit
HYBRID IC BOARD
Ｉ ／Ｆ Ｒ Ｅ Ｌ Ａ Ｙ
Ｍ Ｉ Ｃ Ｒ Ｏ
Ｃ ＯＭ Ｐ Ｕ Ｔ Ｅ Ｒ
Ｒ Ｅ Ｓ Ｅ Ｔ
The reset circuit initializ
Low voltage at pin
52
Fig. 4-1 shows the reset circuit and Fig. 4-2 shows waveform at each point when power is turned on and
off.
When power is turned on, 12V line and 5V line voltages rise and 12V line voltage reaches 10.9V an
reset voltage input to pin
Reset voltage will be hold "Hi" until the 12V line voltage drops to 9.90V even though the power shuts
down.
12
10.9V
6
0
12
6
0
４ ０
Ｒ ２ ２ ５
５ ２
０ Ｖ
es the microcomputer program when Power is "ON" from "OFF"
resets the microcomputer, and HI activates the microcomputer
of microcomputer is set to Hi.
52
12V line
Reset voltage
Ｄ ２ ７ ３
Ｒ ２ ８ ８
５ Ｖ
０ Ｖ
８
６
−
７
＋
５
Ｉ Ｃ ５ （２／２）
Ｒ ２ ８ ５
Fig. 4-1
12V line
5V line
Reset voltage
5V line
Fig. 4-2
66
MAIN
P.W.B.
１ ２ Ｖ
３ ０
＋
０ Ｖ ０ Ｖ
Time
9.9V
Time